1993 grand cherokee keeps stalling

My 93 grand cherokee will start up and idle fine but when i rev it up as soon as i take my foot off the gas it will stall. i had a leaky gas line last summer and a repair place fixed it with some flexible gas line. then i had the stalling problem last summer. left it at the dealership over the weekend and when they looked at it, it would run just fine. they ended up changing the fuel filter and everything was good until last weekend when it started doing the same thing. i dont know if it has to do with the flexible gas lines or not. what do you think? :banghead: